Metal packaging is known in which a can body having a metal ring seamed to one end of the can body supports a peelable lid which comprises a multi-layer membrane having typically a peelable polypropylene layer, a layer of aluminum, and an outer layer of print, lacquer, PET or other coating. The material of the lidding material is generally chosen according to the requirements dictated by the product with which the can body is filled. For example, there is a need for maintaining seal integrity during processing, sterilization etc. of food products but the lid must also be capable of being readily opened for access to the food for consumption.
The use of an intermediate metal ring to support the lidding material is usual for optimum seal integrity. However, the production of this ring leads to substantial wastage of material since the central part of the ring cannot economically be re-used for conventional can component sizes. In addition, the ring may reduce access to the can contents. Manufacturing time using separate stages for manufacturing the ring and fixing the lidding material to this ring is also long. There is therefore a need to provide a container in which the lid is bonded directly to the can body, thereby obviating the need for an intermediate component. Manufacture of the packaging can of the invention is also simplified so as to reduce manufacturing costs, whilst facilitating access to the contents of the finished can.
EP-0819086 describes a process for manufacturing a can with a foil membrane, in which the membrane is preformed with a raised edge and is inserted into the can so that the outside edge region is raised in the direction of the can axis. The edge is then connected to the inside of the can wall by an adhesive bond or heat seal. This process is inherently slow because not only does the foil membrane require preforming but careful handling is needed for location in the can body. The can body also has to be removed from the can making line or pass through one or more separate stations for pressing the membrane onto can body wall.